And I'm Melissa Block. Iraq's largest oil refinery is under attack today by Islamist militants, and the Iraqi capital continues to brace for an assault. The militants, led by ISIS, the Islamic State of Iraq and Syria, have already taken over major cities in the north and west. Iraq's prime minister has appealed for national unity, and he's vowed that government forces will turn the insurgents back. In a moment, we'll hear more about how ISIS is funding its operations. But first, we turn to NPR's Deborah Amos, who joins us from Erbil in northern Iraq. And Deborah, let's talk first about the attack on the oil refinery north of Baghdad. What have you learned about that?

DEBORAH AMOS, BYLINE: Reports started coming in this morning, Melissa, of machine gun and mortar fire on the refinery in Baiji. This is one of the largest in the country. There are three of them. If this falls, this is a big blow to the government. The town had been seized by ISIS earlier. The facility had been shut down due to fighting on Tuesday. German technical workers were evacuated from Baiji. The fighting has gone on all day. An Iraqi military spokesman denied that Baiji had fallen to the rebels. It's very difficult to confirm. What I can tell you is that the shutdown has certainly even affected us here. There are long lines at the gas stations. We took a drive down to interview the latest civilians who are fleeing from the fighting, and you can see it all the way down the highway, that everybody's in line for gas.

BLOCK: Deborah, you mentioned that German workers had been evacuated from that oil refinery in Baiji before the assault. Have other foreign workers been getting caught up in this fighting?

AMOS: Melissa, there are international workers all over this country, in the oilfields, in the hospitals, in construction sites. The Indian government's raised concerns about 60 workers who were seized from a bus when they fled Mosul, trying to get here to Erbil. There is a group of Indian nurses who are working in the town of Tikrit that was taken over by ISIS earlier in the week. And we already know about Turkish diplomatic staff that were kidnapped by ISIS when this crisis began.

BLOCK: President Obama has been calling on the Iraqi government and Prime Minister Nouri al-Maliki, in particular, to be more inclusive of the Sunni population. I mentioned that the prime minister has appealed for national unity. Is there any meat on those bones? I mean, are there any indications that he is making steps in that direction?

AMOS: Well, we saw him on Tuesday do something that he hasn't done, and that is appear with Sunni political leaders on TV. These are some of his fiercest critics. The prime minister said today that the seizure of the second-largest city was a shock. Now, whether it's a big enough shock to reach out to the Sunnis to change the political thinking in Baghdad remains to be seen. Emotions are running high on both sides of the Sunni-Shia divide because sectarian killings are on the rise. The prime minister lashed out at regional powers Saudi Arabia and Qatar. And he accused the Gulf states of being part of a conspiracy against him.

BLOCK: And the regional implications are really important. Saudi Arabia and Iran have been trading blame, pointing fingers at each other over the question of Iraq, highlighting a very intense Sunni-Shiite Muslim divide in the region.

AMOS: Well, this crisis has certainly heated up the rhetoric. The Iranians vowed that they will protect Shiite religious shrines in Iraq. There are millions of Iranian pilgrims who come here to worship. The ISIS militants have vowed to march on those holy cities. The Saudis have long been at odds with Prime Minister Nouri al-Maliki. They see him as an Iranian pawn, and their rhetoric today was very tough on him. They say he has sectarian and exclusionary policies. They also sent a veiled warning to Iran by rejecting what they called foreign interference in Iraq.

BLOCK: NPR's Deborah Amos, speaking with us from Erbil in northern Iraq. Deborah, thanks very much.